A powertrain includes a combustion chamber, an intake assembly, an exhaust manifold, and a pump. The combustion chamber is configured for combusting an air and fuel mixture. The intake assembly is configured to supply air to the combustion chamber. The exhaust manifold is configured to draw exhaust gas from the combustion chamber. The pump is operatively disposed between the intake assembly and the exhaust manifold such that the pump is in fluid communication with each of intake assembly and the exhaust manifold. The pump is configured to operate in a first mode to draw exhaust gas from the exhaust manifold and supply the exhaust gas to the intake manifold at a positive egr flow rate such that exhaust gas is supplied to the combustion chamber.
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1. A powertrain comprising:
a combustion chamber configured for combusting an air and fuel mixture;
an intake assembly configured to supply air to the combustion chamber;
an exhaust manifold configured to draw exhaust gas from the combustion chamber; and
a pump operatively disposed between the intake assembly and the exhaust manifold such that the pump is in fluid communication with each of the intake assembly and the exhaust manifold;
wherein the pump is configured to operate in a first mode to draw exhaust gas from the exhaust manifold and supply the exhaust gas to the intake manifold at a positive egr flow rate such that exhaust gas is supplied to the combustion chamber, and
wherein the pump is also configured to operate in a second mode to draw fresh air from the intake assembly at a fresh air intake flow rate and supply the fresh air directly to the exhaust manifold such that the fresh air entering the exhaust manifold mixes with the exhaust gas entering the exhaust manifold to increase the oxygen content within the exhaust gas and to increase a combustion temperature of the exhaust gas exiting the exhaust manifold.
8. A method of controlling a pump of an emission system operatively connected to an intake assembly and an exhaust manifold of an internal combustion engine, the method comprising:
determining a nox concentration of exhaust gas in the exhaust manifold;
determining the nox concentration of exhaust gas is at least equal to a nox concentration limit;
determining a positive egr flow rate required to lower the determined nox concentration to below the nox concentration limit; and
commanding the pump to operate in a first mode to achieve the positive egr flow rate until the nox concentration is determined to be below the nox concentration limit;
determining an exhaust gas temperature;
determining the exhaust gas temperature is less than a required minimum exhaust gas temperature;
determining a fresh air intake flow rate required to raise the exhaust gas temperature to be at least equal to the required minimum exhaust gas temperature; and
commanding the pump to operate in a second mode to achieve the fresh air intake flow rate to draw fresh air from the intake assembly at the fresh air intake flow rate and supply the fresh air directly to the exhaust manifold such that the fresh air entering the exhaust manifold mixes with the exhaust gas entering the exhaust manifold to increase the oxygen content within the exhaust gas and to increase a combustion temperature of the exhaust gas exiting the exhaust manifold.
12. A method of controlling a pump of an emission system operatively connected to an intake assembly and an exhaust manifold of an internal combustion engine, the method comprising:
determining a pressure differential between the exhaust manifold and the intake assembly;
determining a required pressure differential between the exhaust manifold and the intake assembly to provide a desired fuel efficiency of the internal combustion engine;
determining whether the determined pressure differential is at least equal to a required pressure differential;
commanding the pump to operate in a first mode to achieve the positive egr flow rate such that required pressure differential is achieved;
determining an exhaust gas temperature;
determining the exhaust gas temperature is less than a required minimum exhaust gas temperature;
determining a fresh air intake flow rate required to raise the exhaust gas temperature to be at least equal to the required minimum exhaust gas temperature; and
commanding the pump to operate in a second mode to achieve the fresh air intake flow rate to draw fresh air from the intake assembly at the fresh air intake flow rate and supply the fresh air directly to the exhaust manifold such that the fresh air entering the exhaust manifold mixes with the exhaust gas entering the exhaust manifold to increase the oxygen content within the exhaust gas and to increase a combustion temperature of the exhaust gas exiting the exhaust manifold.
2. A powertrain, as set forth in
wherein exhaust gas is prevented from flowing between the exhaust manifold and the intake assembly when the egr valve is in the closed position; and
wherein the exhaust gas is allowed to flow between the exhaust manifold and the intake assembly when the egr valve is in the open position.
3. A powertrain, as set forth in
wherein the pump is configured to operate in the first mode if the determined concentration of nox in the exhaust manifold is determined to require an increased positive egr flow rate.
4. A powertrain, as set forth in
wherein the cooler is configured to cool the exhaust gas received from the exhaust manifold.
6. A powertrain, as set forth in
wherein the pump is configured to operate in the second mode when the temperature of the exhaust gas is determined to be less than a required minimum exhaust gas temperature.
7. A powertrain, as set forth in
9. A method, as set forth in
10. A method, as set forth in
11. A method, as set forth in
determining whether an exhaust gas recirculation valve is in an open position; and
wherein commanding the pump to operate in a first mode is further defined as commanding the pump to operate in a first mode to achieve the positive egr flow rate when the exhaust gas recirculation valve is in the open position.
13. A method, as set forth in
determining whether an exhaust gas recirculation valve is in an open position; and
wherein commanding the pump to operate in a first mode is further defined as commanding the pump to operate in a first mode to achieve the positive egr flow rate when the exhaust gas recirculation valve is in the open position.
14. A method, as set forth in
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The present disclosure relates to an emission system and method of selectively directing exhaust gas within an internal combustion engine.
Internal combustion engines may re-circulate exhaust gas from the exhaust system to an intake manifold, typically referred to as Exhaust Gas Recirculation (EGR), to improve fuel efficiency of the vehicle and/or reduce engine emissions. Because the exhaust gas from the EGR system is directed to the intake manifold, the necessary operation of the EGR system, e.g., the fuel/air mixture ratio, may need to vary from the various operating conditions, and the amount of exhaust gas delivered by the dedicated EGR cylinders may need to be regulated.
A powertrain includes a combustion chamber, an intake assembly, an exhaust manifold, and a pump. The combustion chamber is configured for combusting an air and fuel mixture. The intake assembly is configured to supply air to the combustion chamber. The exhaust manifold is configured to draw exhaust gas from the combustion chamber. The pump is operatively disposed between the intake assembly and the exhaust manifold such that the pump is in fluid communication with each of intake assembly and the exhaust manifold. The pump is configured to operate in a first mode to draw exhaust gas from the exhaust manifold and supply the exhaust gas to the intake manifold at a positive EGR flow rate such that exhaust gas is supplied to the combustion chamber.
A method of controlling a pump of an emission system that is operatively connected to an intake assembly and an exhaust manifold of an internal combustion engine includes determining a NOx concentration of the exhaust gas in the exhaust manifold. A determination is made as to whether the determined NOx concentration is at least equal to a NOx concentration limit. A determination is made as to whether a positive EGR flow rate required to lower the determined NOx concentration to below the NOx concentration limit. The pump is commanded to operate in a first mode to achieve the positive EGR flow rate.
In another aspect, a method of controlling a pump of an emission system that is operatively connected to an intake assembly and an exhaust manifold of an internal combustion engine includes determining a pressure differential between the exhaust manifold and the intake assembly. A determination is made as to whether a required pressure differential between the exhaust manifold and the intake assembly to provide a desired fuel efficiency of the internal combustion engine. A determination is made as to whether the determined pressure differential is at least equal to a required pressure differential. The pump is commanded to operate in a first mode to achieve the positive EGR flow rate such that required pressure differential is achieved.
The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings.
Referring to the Figures, wherein like numerals indicate like parts throughout the several views, a vehicle is generally shown at 20 in
The combustion chamber 32 is configured for combusting an air/fuel mixture to provide drive torque to propel the wheels 28 of the vehicle 20. Air may enter the combustion chamber 32 of the internal combustion engine 24 by passing through an air filter (not shown) before entering the intake assembly 34. Therefore, the intake assembly 34 supplies air into the combustion chamber 32. Fuel is injected into the combustion chamber 32 to mix with the air, which provides an air/fuel mixture. Spark plugs (not shown) ignite the air/fuel mixture within the combustion chamber 32. Combustion of the air/fuel mixture creates exhaust gas. The exhaust gas exits the combustion chamber 32 and is drawn into the exhaust manifold 36.
With continued reference to
The increase in the exhaust gas that mixes with the air-fuel mixture inside of the combustion chamber 32 reduces the formation of locally rich, high temperature regions that contribute to soot formation. The positive EGR flow rate allows the exhaust gases to then act as diluents that suppress the temperature of combustion below that which significant amounts of mono-nitrogen oxides (NOx) are formed. The pump 38 may selectively operate at variable speeds in the first mode to vary the EGR flow rate, thus varying control of the temperature of combustion and formation of NOx. Therefore, a speed of the pump 38 may be increased in the first mode to increase the positive EGR flow rate. Likewise, the speed of the pump 38 may be decreased in the first mode, or otherwise turned off, to decrease the positive EGR flow rate.
Referring again to
The emission system 26 may also include a cooler 42 that is disposed in fluid communication with the exhaust manifold 36 and the EGR valve 40. More specifically, the cooler 42 may be operatively disposed between the exhaust manifold 36 and the pump 38. As such, the cooler 42 is configured to cool the exhaust gas received from the exhaust manifold 36, prior to mixing the exhaust gases with the ambient air in the intake assembly 34.
When the pump 38 is selectively operating in the second mode, a pressure differential is generated between the intake assembly 34 and the exhaust manifold 36, resulting in a fresh air intake flow. In the second mode, the negative pressure differential, created by operation of the pump 38, draws air from the intake assembly 34 and supplies the air to the exhaust manifold 36 via secondary air injection (SAI) to mix with the exhaust gas. More specifically, during cold starting of the vehicle 20, there is a scarcity of oxygen in the exhaust gas entering the exhaust manifold 36. The scarcity of oxygen in the exhaust gas may limit the extent of any exothermic chemical reaction in the exhaust manifold 36 and/or the catalyst within a catalytic converter 43. Therefore, the mixture of the air with the exhaust gas within the exhaust manifold 36 during cold starts increases the oxygen content within the exhaust gas, allowing additional combustion of the exhaust gas to increase the exhaust temperature into the catalytic converter 43. More specifically, this higher temperature increase may result in a faster catalyst light-off by a catalyst in the catalytic convertor 43, allowing for a reduction of the NOx, HC, and CO in the exhaust gas during cold starting.
As shown in
The control system 44 may include one or more components with a storage medium and a suitable amount of programmable memory, which are capable of storing and executing one or more algorithms or methods to effect control of the powertrain 22. Each component of the control system 44 may include distributed controller architecture, and may be part of the ECU 46. Additional modules or processors may be present within the control system 44.
Still referring to
Additionally, the ECU 46 can be configured as a general purpose digital computer generally comprising a microprocessor or central processing unit, read only memory (ROM), random access memory (RAM), electrically-programmable read only memory (EPROM), high speed clock, analog to digital (A/D) and digital to analog (D/A) circuitry, and input/output circuitry and devices (I/O), as well as appropriate signal conditioning and buffer circuitry. Any algorithms resident in the ECU 46 or accessible thereby, can be stored in ROM and executed to provide the respective functionality.
The ECU 46 is configured to selectively move the EGR valve 40 between the open position and the closed position. The ECU 46 also configured to selectively operate the pump 38 in the first mode, the second mode, or not at all. Further, the ECU 46 may be configured to operate the pump 38 at any desired speed or mode to vary the EGR flow rates, as required. Thus, when the pump 38 is operating in the first mode, higher positive EGR flow rates may be attained in regions of vehicle 20 engine operation that would typically result in a limited pressure differential. As such, improved engine fuel efficiency can be attained. Further, since the pump 38 is also allowed to operate in the second mode to achieve the fresh air flow rate during vehicle 20 cold starts to provide SAI to the exhaust manifold 36, emission system 26 hardware is minimized.
Referring now to
For illustrative purposes, the method 100 is described with reference to elements and components shown and described in relation to
Referring again to
A determination of the exhaust gas temperature is made at step 112. The determination may be made using one or more of the sensors 48, empirically, using look-up tables, and the like.
At step 114, the determined exhaust gas temperature may be compared with a required minimum exhaust gas temperature. If the determined exhaust gas temperature is not at least equal to the required minimum exhaust gas temperature, then the pump 38 may operate in the second mode at step 116, as described above.
If the determined exhaust gas temperature is determined to be at least equal to the required minimum exhaust gas temperature, then a determination of whether the EGR valve 40 is in the open position is made at step 118. If the EGR position is determined to not be in the open position, i.e., is in the closed position, then, at step 120 the pump 38 does not operate in any mode.
If the EGR position is determined to be in the open position, then at step 122, a determination of the NOx concentration of the exhaust gas is made. This determination may be made using one or more of the sensors 48, empirically, using look-up tables, and the like.
At step 124, a determination is made as to whether the NOx concentration needs to be reduced to below a NOx concentration limit. If the determination is made at step 124 that the NOx concentration does not require reduction, the method 100 then proceeds to step 120 so that the pump 38 does not operate in any mode.
If, however, at step 124, a determination is made that the NOx concentration does need to be reduced to below the NOx concentration limit, a positive EGR flow rate required to lower the determined NOx concentration to below the NOx concentration limit is determined. The method 100 then proceeds to step 126, which commands the pump 38 to operate in the first mode to reduce the NOx concentration of the exhaust gas to below the NOx concentration limit.
While the best modes for carrying out the disclosure have been described in detail, those familiar with the art to which this disclosure relates will recognize various alternative designs and embodiments for practicing the disclosure within the scope of the appended claims.
Loveland, Dustin P, Kohler, Jason G.
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